This invention relates generally to a sterilizing method for treatment of fresh fruits and an apparatus used for the method.
Conventionally, fresh fruits produced in tropical areas are either sterilized in saturated steam heat-treatment facilities by heating. For example in the case of mangoes, the fruits are heated at a temperature higher than 46.0.degree. C. for 10 minutes so that the cores of the fruits are kept at 46.degree. C. or are treated in fumigation facilities by fumigating the fruits with ethylene dibromide or other fumigation agents at a temperature higher than 26.degree. C. for 2 hours.
While the first sterilizing method using saturated steam has the disadvantage of a high treatment cost since it consumes a large quantity of saturated steam for treatment, the second sterilizing method using ethylene dibromide or other fumigation agents is accompanied by the problem of health hazards in that such fumigation agents are highly toxic.
Apart from these methods, recently attention has been paid to far infrared rays that are on the long wave length side of the infrared spectrum since irradiation of such rays on an object causes resonance-absorption in the object, a phenomenon in which the object absorbs energy from the projected far infrared rays and heats itself from the inside when it contains molecules having inherent frequencies that coincide with those of the projected rays to effect resonance. This phenomenon is of particular interest in terms of heating with low energy consumption.